My mother has recently asked me to help her weed the lawn and flower beds. No matter how much we pull they keep popping up through the mulch. Is there any chemical treatment you would recommend? I've looked and they all seem to say that they are the #1 weed killer.

After I plant my bedding plants and mulch them I sprinkle on a pre-emergence product such as Preen or Miracle Grow's weed preventer with fertilizer. It prevents weeds from germinating.
Dorothy Nichols, author of Garden Adventures

I mulch heavy and since my recent knee surgery ( that stops me from bending over much), I now weed with roundup. I choose a very calm day, and i get really close to each weed and just allow the sprayer to drip roundup on each weed. This works best for me and my condition. Just remember that the roundup will kill anything green it touches so you have to be very careful.